Is the Pond Water Safe for Livestock?

During the hottest part of summer, a farm pond can look like a welcome source of water. Cattle may be standing belly-deep along the bank, and the pond may still hold enough water to appear dependable. However, appearance alone does not reveal whether that water is safe.

Hot weather, limited rainfall and falling pond levels can create water-quality problems. As water evaporates, salts, minerals, nutrients and other substances may become more concentrated. Warm, still water can also encourage the growth of blue-green algae, some forms of which can produce toxins capable of killing livestock.

Water is sometimes treated as an afterthought compared to grass, hay and supplemental feed. In reality, livestock need a dependable supply of clean water to maintain feed intake, regulate body temperature and support production. Poor-quality water may reduce consumption and performance even when it does not cause an obvious case of poisoning.

A pond that has watered cattle for years should not automatically be considered safe under every set of conditions. Producers should pay particular attention during drought, extreme heat or any period when the water level drops significantly.

Watch the Water and the Livestock

One of the most serious late-summer concerns is a bloom of cyanobacteria, commonly called blue-green algae. These organisms are naturally present in many bodies of water, and most do not produce dangerous toxins. The risk increases when certain toxin-producing species multiply rapidly under favorable conditions.

According to Oklahoma State University Extension, toxic blue-green algal blooms typically develop in standing water following periods of hot, dry and calm weather. Nutrients such as nitrogen and phosphorus can contribute to excessive growth. Those nutrients may enter a pond through manure, fertilizer runoff, soil erosion and decaying vegetation.

A suspicious bloom may make the water appear bright green, blue-green, pea-soup green or even brownish. Scum, foam or mats may collect along the shoreline, particularly where the wind pushes floating material into one area. Some blooms resemble spilled paint.

Not every green pond is poisonous. Common aquatic plants and harmless forms of algae can also change the color or surface of the water. Unfortunately, it is usually impossible to determine whether a bloom is toxic simply by looking at it. A pond can contain toxin-producing cyanobacteria without displaying every commonly described warning sign.

Owners should keep livestock, horses, pets and people away from water that has an unusual color, heavy surface scum, a bad odor or unexplained dead fish or wildlife nearby. Livestock should not be allowed to drink from another portion of the same pond under the assumption that the water is safe there. Wind can move a bloom, and toxin concentrations may vary throughout the pond.

Blue-green algae can produce toxins that affect the nervous system or liver. Depending on the toxin and the amount consumed, affected animals may develop weakness, staggering, difficulty breathing, tremors, convulsions, diarrhea or collapse. In severe cases, animals may be found dead near the water before the owner realizes anything is wrong. Treatment is often unsuccessful, making prevention especially important.

Any suspected poisoning should be treated as an emergency. Remove the herd from the water source without driving or unnecessarily stressing animals that may already be affected. Provide another clean water supply and contact a veterinarian immediately. The local county Extension office can also help determine where and how to submit an appropriate water sample.

Blue-green algae is not the only potential problem. Pond water may contain elevated levels of dissolved salts, sulfates, nitrates, bacteria or other contaminants. Runoff can carry manure, fertilizer, pesticides and organic matter into the pond. Low water levels can make some of these problems more pronounced because the remaining water becomes increasingly concentrated.

Water with excessive dissolved solids may taste bitter or salty, reducing the amount animals consume. Depending on the substances involved and their concentrations, poor-quality water may contribute to diarrhea, reduced feed intake, poor weight gain or other health concerns. Young animals and livestock that are not accustomed to the water may be more vulnerable.

Producers should also watch the cattle themselves. Are they reluctant to drink? Are they crowding around a different water source? Has feed intake or weight gain declined without an obvious explanation? Are several animals experiencing digestive problems? Changes involving multiple animals can provide an early clue that feed or water should be investigated.

OSU Extension recommends collecting a representative sample and submitting it for a livestock water test when a water supply is suspected of harming animal health or performance. A standard livestock water test may evaluate several characteristics, but blue-green algae concerns can require different sampling and testing procedures. Producers should contact the laboratory or county Extension office before collecting the sample so it is taken from the correct location, placed in the proper container and handled appropriately.

Reduce Problems Before They Develop

Good pond management cannot eliminate every water-quality problem, but it can lower the risk. One of the most effective steps is limiting the amount of manure, soil and nutrients that enter the water.

Allowing cattle unrestricted access to an entire pond can result in damaged banks, muddy water and large amounts of manure being deposited in or near the water. Hoof traffic removes vegetation and contributes to erosion. Sediment fills the pond over time, while manure supplies nutrients that may encourage excessive algae growth.

Where practical, fencing livestock away from most of the pond and providing a limited-access watering point can improve conditions. Another option is piping water to a trough located below the dam or elsewhere in the pasture. OSU notes that reducing cattle excrement in the pond can decrease conditions favoring toxic algae and improve water palatability.

A vegetated buffer around the pond can also slow runoff and help trap soil and nutrients before they reach the water. Fertilizer and manure should be applied carefully in the watershed, particularly before heavy rainfall. Producers should avoid allowing large amounts of hay, feed or organic debris to accumulate at the water’s edge.

Alternative watering systems require maintenance, too. Troughs should be checked for algae, manure, drowned animals and other contamination. Wildlife escape ramps should be installed in tanks so birds and small animals can climb out rather than drowning and contaminating the water.

Owners should be cautious about treating a pond on their own. Copper sulfate and other algaecides are sometimes used for algae control, but improper treatment can create additional problems. Killing a large quantity of algae or aquatic vegetation at one time can reduce dissolved oxygen as the material decomposes, potentially leading to a fish kill. Treatment may also release toxins from affected cyanobacteria into the water. Any chemical application should be based on proper identification and professional recommendations rather than guesswork.

Livestock should always have access to enough water for the weather, their size and their stage of production. Demand increases sharply during hot weather, and a pond that barely meets the herd’s needs in spring may not be sufficient in August. Check the source regularly rather than waiting for cattle to gather around a muddy shoreline.

A safe-looking pond is not necessarily safe, and a green pond is not necessarily toxic. That uncertainty is exactly why observation, testing and prevention matter. When the water changes color, develops surface scum, gives off an unusual odor or coincides with unexplained animal illness, move livestock to another source and seek professional guidance.

The condition of the pond affects more than where cattle take a drink. It can influence feed intake, performance and the health of the entire herd. During late summer, checking the water deserves a place alongside checking grass, mineral and body condition.